An ordinary organic light emitting device has a stacked structure for maximizing light emitting efficiency through recombination of holes and electrons. Glass is used for a substrate, indium tin oxide (ITO) that is transparent and has a high work function and conductivity is used for an anode, and a metal having a low work function such as Mg/Ag or Al is used for a cathode. Holes injected from an anode and electrons injected from a cathode are recombined in an organic material layer that is an emission layer to generate excitons. As the excitons diffuse, light corresponding to a band gap of the emission layer is emitted toward a transparent electrode. A display device using the organic light emitting device can realize a good display image without drawbacks associated with image sticking and viewing angle. Further, the display device using the organic light emitting device has low power consumption because it is a self-light emitting device that does not require backlight. In addition, the organic light emitting device may be more affordable by more customers due to the low cost because it can be manufactured at a low temperature through simple processes. In particular, a flexible organic light emitting device has been focused recently because degree of freedom of a product can be remarkably improved.
To manufacture a flexible organic light emitting device, a method of manufacturing an organic light emitting device on a mother substrate such as a thin glass substrate, a metal substrate and a plastic substrate have been studied, however, there are several limitations to be overcome. The thin glass substrate has a limitation in the flexibility. On the other hand, a rough surface of the metal substrate causes a decrease of device characteristic, and a good conductivity thereof generates electrical interference between devices. When a plastic substrate is used, there is a difficulty in chemical treatment. Further, there is also a difficulty in pattern formation and substrate alignment because the plastic substrate is too flexible. Therefore, mass production is difficult. In particular, since the plastic substrate has a low thermal stability, the process should be performed at a low temperature. Therefore, it is difficult to decrease a resistance of indium tin oxide (ITO) used for a cathode of the organic light emitting device to a value below 70 ohm/cm2, by which an operation voltage of the organic light emitting device is increased. Additionally, a sealing process and a manufacturing process of an electric field device cannot be performed at a high temperature, which leads to a decrease in device characteristics.
As described above, there are limitations in manufacturing a flexible device, and even though the flexible device is manufactured, the device characteristic becomes poor compared to typical other devices.